• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.178-188
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• 2024

The dynamics of suspended sediment (SS) in forested catchments vary depending upon human or natural disturbances, including land use change, forestry activity, forest fires, and landslides. Understanding the dynamics of SS originating from the potential sources within a forested catchment is crucial for establishing an effective water quality management strategy. Therefore, to suggest a systematic method for interpreting SS dynamics, we evaluated the performance and applicability of ten methods for calculating the hysteresis index based on observed hydrological data and two calculation models (Lawler's method and Lloyd's method) with five sampling intervals (50th, 25th, 10th, 5th, and 1st percentiles). Our results showed that Lloyd's method, which used a sampling interval at the 1st percentile, had the largest number of analyzable runoff events and exhibited the best performance. The results of this study can contribute to quantifying the hysteresis in the relationship between discharge and SS and provide useful information for interpreting SS dynamics.

• The Korean Journal of Quaternary Research
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• v.34 no.1
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• pp.41-51
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• 2024

The Sincheon wetland shows a remarkable diversity of fluvial landforms, such as river islands, anastomosing channels, braided channels, and sand-gravel bars, which contribute to its rich ecological habitat. The wetland area is characterized by a ecological diversity of herbaceous and woody plants. Significant changes in land cover within the wetlands were observed from 2008 to 2020. Notably, there was a rapid decrease in agricultural area from 18% to 0.04%, while the vegetation area expanded from 45% to 54%. Concurrently, the water area also experienced a notable increase from 34% to 41%. The surface sediment composition in the studied area displays sandy loam characteristics and exhibits acidic soil properties. Sediment acidity tends to increase downstream and in the central part of channels. Variations in acidity are also observed at nearby collection sites due to the tributaries and local discharge. The presence of dense vegetation in river islands and bars has led to a significant transformation of sediments into soil, with this change being more pronounced downstream, particularly near the weirs. The installation of a weir in Sincheon wetland is believed to have a significant impact on altering flow velocities between upstream and downstream sections, as well as influencing erosion and sediment deposition patterns. However, given the formation of landforms in response to weirs, effective administration and management are essential to address potential risks of catastrophic environmental disruptions, such as the removal of weirs and/or the maintenance of river channels.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.600-612
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• 2021

Purpose To evaluate the long-term radiologic and clinical outcomes of stent-graft placement for the treatment of post-pancreaticoduodenectomy arterial hemorrhage (PPAH) based on the imaging findings of stent-graft patency and results of liver function tests. Materials and Methods We retrospectively reviewed the medical records of nine consecutive patients who underwent stent-graft placement for PPAH between June 2012 and May 2017. We analyzed the immediate technical and clinical outcomes and liver function test results. Stent-graft patency was evaluated using serial CT angiography images. Results All stent-grafts were deployed in the intended position for the immediate cessation of arterial hemorrhage and preservation of hepatic arterial blood flow. Technical success was achieved in all nine patients. Eight patients survived after discharge, and one patient died on postoperative day 28. The median follow-up duration was 781 days (range: 28-1766 days). Follow-up CT angiography revealed stent-graft occlusion in all patients. However, serum aspartate aminotransferase or alanine aminotransferase levels in all patients were well below those observed in hepatic infarction cases. Conclusion Stent-graft placement is a safe and effective treatment method for acute life-threatening PPAH. Liver function and distal hepatic arterial blood flow were maintained postoperatively despite the high incidence of stent-graft occlusion observed on follow-up CT.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.93-105
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• 2024

Purpose: This study aims to quantitatively determine the impact on nearby risidents by selecting the amount of chemicals emitted from the workplace among the substances subject to the chemical emission plan and predicting the concentration with the atmospheric diffusion program. Method: The selection of research materials considered half-life, toxicity, and the presence or absence of available monitoring station data. The areas discharged from the materials to be studied were selected as the areas to be studied, and four areas with floating populations were selected to evaluate health risks. Result: AERMOD was executed after conducting terrain and meteorological processing to obtain predicted concentrations. The health hazard assessment results indicated that only dichloromethane exceeded the threshold for children, while tetrachloroethylene and chloroform appeared at levels that cannot be ignored for both children and adults. Conclusion: Currently, in the domestic context, health hazard assessments are conducted based on the regulations outlined in the "Environmental Health Act" where if the hazard index exceeds a certain threshold, it is considered to pose a health risk. The anticipated expansion of the list of substances subject to the chemical discharge plan to 415 types by 2030 suggests the need for efficient management within workplaces. In instances where the hazard index surpasses the threshold in health hazard assessments, it is judged that effective chemical management can be achieved by prioritizing based on considerations of background concentration and predicted concentration through atmospheric dispersion modeling.

• Clinical and Experimental Pediatrics
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• v.48 no.2
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• pp.158-164
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• 2005

Purpose : We reviewed the therapeutic results of various Duct-Occlud coils(pfm AG, $K{\ddot{o}}ln$, Germany) to evaluate the efficacy of the most-recently modified Duct-Occlud coil(Nit-Occlud) in the transcatheter closure of patent ductus arteriosus(PDA), including large defects more than 4 mm in diameter. Methods : Two hundred and five patients who underwent percutaneous PDA occlusion using Duct-Occlud devices from March 1996 to December 2003 were enrolled and four types of Duct-Occlud [Standard(S), Reinforced(R), Reinforced reverse cone(RR) and Nit-Occlud(N)] were used in this study. The patients were followed up by echocardiogram and physical examination before discharge, one month, six months and 12 months after the procedure. Results : The rate of residual shunt according to the type of Duct-Occlud were as follows : S-54%, R-72%, RR-50%, N-14%(P<0.05 compared with other devices) at one month, S-25%, R-44%, RR-37%, N-0%(P<0.05 compared with other devices) at six months, S-8%, R-8%, RR-4%, N-0%(P<0.05 compared with S and R) at 12 months and later. Nit-Occlud coil showed the complete occlusion of PDA after six months of follow-up, even in 12 patients with relatively large PDA(>4 mm). Conclusion : The transcatheter closure of PDA using Duct-Occlud was an effective treatment and our study revealed that a Nit-Occlud coil which showed higher rate of occlusion even in PDA with large diameters over than 4 mm, was a more effective modality compared to previous devices.

• Clinical and Experimental Pediatrics
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• v.53 no.3
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• pp.358-364
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• 2010

Purpose : The aim of this study was to determine the efficacy of $Synagis^{(R)}$ (palivizumab) in reducing the respiratory syncytial virus (RSV) readmission rate in very low birth weight infants (VLBWI ) and the subgroup that showed the most effective vaccination. Methods : We enrolled 350 VLBWI who had been discharged alive from the neonatal intensive care unit of Samsung Medical Center from January 2005 to December 2007 and were followed up for at least one year. A retrospective study based on medical records was performed for a period of one year after discharge. RSV readmission rate was investigated according to BPD (bronchopulmonary dysplasia, requiring oxygen at postnatal day 28) and $Synagis^{(R)}$ prophylaxis. We categorized the subgroups by the severity of BPD gestational age, and birth weight and compared the RSV readmission rates between subgroups. Results : Eleven VLBWI were readmitted. $Synagis^{(R)}$ prophylaxis resulted in a 86% reduction in the rate of readmission due to RSV infection (prophylaxis group, 0.7% and no prophylaxis group, 5.0%; P =0.02). Readmission rate in BPD patients was also reduced in the prophylaxis group (0.7% in the prophylaxis group vs. 5.2% in the no prophylaxis group, P =0.03). The readmission rate in patients without BPD was reduced in the prophylaxis group (0% in the prophylaxis group vs. 4.9% in the no prophylaxis group, P =1.00), but this was not statistically significant.Conclusion : $Synagis^{(R)}$ prophylaxis was effective at reducing RSV readmission in VLBWI. Its efficacy was verified irrespective of BPD, gestational age, or birth weight.

• Membrane Journal
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• v.21 no.1
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• pp.22-29
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• 2011

During the maintenance, repair and replacement process of circuit breaker, $SF_6$ reacted with input air in arc discharge, which led to the production of by-product gases (eg, $N_2$, $O_2$, $CF_4$, $SO_2$, $H_2O$, HF, $SOF_2$, $CuF_2$, $WO_3$). Among these various by-product gases, $N_2$, $O_2$, $CF_4$ is major component. Therefore, the effective separation process is necessary to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. In this study, the membrane separation process was applied to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. The concentration of $SF_6$ gas in gas produced from the electric power industry is over than 90 vol%. Therefore, we made the simulated gas containing $N_2$, $O_2$, $CF_4$, $SF_6$ which the concentration of $SF_6$ gas is minimum 90 vol%. From the results of membrane separation process of $SF_6$ gas from $N_2$, $O_2$, $CF_4$ $SF_6$ mixture gases, PSF membrane shown the highest recovery efficiency 92.7%, in $25^{\circ}C$ and 150 cc/min of retentate flow rate. On the other hand, PC membrane shown the highest recovery efficiency 74.8%, in $45^{\circ}C$ and 150 cc/min of retentate flow rate. Also, the highest rejection rate of $N_2$, $O_2$, $CF_4$ is 80, 74 and 58.9% seperately in the same operation condition of highest recovery efficiency. From the results, we supposed the membrane separation process as the effective $SF_6$ separation and recycle process from the mixture gas containing $N_2$, $O_2$, $CF_4$, $SF_6$.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.149-157
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• 2013

The weirs built so far are mainly overflow type weirs overflowing to the upstream. Main advantages of overflow type weirs are, effective water resources management and easy design, construction and maintenance due to many accumulated studies. However, due to the special feature of the overflow type weir where water overflows through the upstream of the weir, the silt coming from the upstream is not discharged to the downstream of the weir. This increases the river bed and reduces the reservoir capacity, and as a result, the weir loses its function. A underflow type weir with a water gate has been implemented in order to solve such sediment deposit and weir maintenance problems. However due to the design problem of recently constructed underflow type weirs, the river bed of the downstream of a weir has been scoured. And this leds to a structural problem. In this study, the flow characteristics of overflow type weirs and underflow type weir, hydraulic jump length analysis depending on change of water depth and the amount of specific energy loss generated per unit length depending on a weir type have been compared and analyzed, for the effective design and management of the weirs. The experiment results show that, when identical upstream conditions of underflow type weir and an overflow type weir were maintained, the hydraulic jump length was up to twice longer with Fr(Froude number) 3.5 of the hydraulic jump length at the underflow type weir, and the hydraulic jump length gradually decreased as the downstream water depth increased. The comparative analysis result of the amount of specific energy loss generated per unit length showed that the amount of energy loss per unit length was twice higher for an overlfow type weir than a underflow type weir. Therefore, in case of a underflow type facility, an additional energy reduction facility is determined to be necessary for safety of water construction structures.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.441-447
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• 2007

Internal derangement of the temporomandibular joint(TMJ) is defined as an abnormal relationship of the articular disc to the condyle. Mandibular manipulation is one of the conservative treatments to be considered first to manage the patients with anterior disc displacement without reduction. Mandibular manipulation is used to increase articular mobility and to restore the displaced disc into an anatomically normal position. While Farrar's technique has been popularly used, Minagi et al., Mongini and Suarez introduced the manipulation technique conducted by the patients themselves. But there is no study on the efficacy of self-manipulation technique, comparing with conventional one. The aim of this study was to investigate the efficacy of the conventional and self-manipulation technique, which was modified to complement the previously described technique by Minagi et al., in the treatment of patients with anterior disc displacement without reduction. TMD patients, who visited Department of Oral Medicine of Seoul National University Dental Hospital from December, 2002 to November, 2004 and were diagnosed as anterior disc displacement without reduction by TMJ magnetic resonance imaging (MRI) were enrolled. Conservative treatments including physical therapy, exercise, behavioral therapy, stabilization splint therapy, and manipulation therapy were done to every single patient until the symptomsimproved enough to discharge the patient. The charts were reviewed retrospectively according to the type of manipulation. In the results, patients whose maximum mouth opening was more than 40 mm was higher in the self-manipulation group(69.9%) than in the conventional manipulation group(42.9%). But difference between two groups was not significant. According to the fact that we decided to discharge the patients whentheir mouth opening increased to more than 40 mm and subjective symptoms such as pain and discomfort were improved as well, treatment period of discharged patients was significantly shorter in the self-manipulation group($29.2{\pm}12.3$ weeks) than in the conventional manipulation group ($61.0{\pm}38.0$ weeks) (p<0.01). In conclusion, in the treatment of TMD patients with anterior disc displacement without reduction, the self-manipulation technique which is performed by patients themselves is an effective treatment modality for increasing the range of mouth opening and shortening the total treatment period.

• Tuberculosis and Respiratory Diseases
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• v.57 no.4
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• pp.329-335
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• 2004

Background : The Sequential Organ Failure Assessment (SOFA) score can help to assess organ failure over time and is useful to evaluate morbidity. The aim of this study is to evaluate the performance of SOFA score as a descriptor of multiple organ failure in critically ill patients in a local unit hospital, and to compare with APACHE III scoring system. Methods : This study was carried out prospectively. A total of ninety one patients were included who admitted to the medical intensive care unit (ICU) in Chuncheon Sacred Heart Hospital from May 1 through June 30, 2000. We excluded patients with a length of stay in the ICU less than 2 days following scheduled procedure, admissions for ECG monitoring, other department and patients transferred to other hospital. The SOFA score and APACHE III score were calculated on admission and then consecutively every 24 hours until ICU discharge. Results : The ICU mortality rate was 20%. The non-survivors had a higher SOFA score within 24 hours after admission. The number of organ failure was associated with increased mortality. The evaluation of a subgroup of 74 patients who stayed in the ICU for at least 48 hours showed that survivors and non-survivors followed a different course. In this subgroup, the total SOFA score increased in 81% of the non-survivors but in only 21% of the survivors. Conversely, the total SOFA score decreased in 48% of the survivors compared with 6% of the non-survivors. The non-survivors also had a higher APACHE III score within 24 hours and there was a correlation between SOFA score and APACHE III score. Conclusion : The SOFA score is a simple, but effective method to assess organ failure and to predict mortality in critically ill patients. Regular and repeated scoring enables patient's condition and clinical course to be monitored and better understood. The SOFA score well correlates with APACHE III score.